The mitochondrion, "the powerhouse of the cell." Somewhere back in the very distant past, something like a bacterium moved into another cell and never left, retaining some of its own DNA. For billions of years, mitochondria have passed from mother to offspring of most eukaryotic organisms, generating energy for the cell and playing roles in metabolism and programmed cell death.
All eukaryotes have them, but that does not mean that all mitochondria are the same. The mitochondria of plants are in fact quite different from those of animals. A new paper published Aug. 30 in PLOS Genetics by Alex Kozik, Beth Rowan and Richard Michelmore at the UC Davis Genome Center and Alan Christensen (who was on sabbatical at UC Davis from the University of Nebraska-Lincoln) shows just how different.
Plant mitochondrial genomes are larger and more complex than those in animal cells. They can vary considerably in size, sequence and arrangement, although the actual protein-coding sequences are conserved.
Plant mitochondrial genomes are almost universally believed to be single circular chromosomes (master circles) and scientific papers and textbooks typically show them as such, write Kozik and colleagues. But in recent years it has become evident that they are much more complex.
